The present invention relates to a gate valve and also a line blind valve having a specific construction of internal components including an elastomer sleeve and a stiffener ring which result in improved operation in sealing of the gate or blind. The gate valve and line blind valve of the present invention are particularly well suited for use with abrasive and corrosive slurries such as are encountered in the pulp and paper industry.
The line blind valve of the present invention is specifically constructed to meet the requirements for line blind service, whereby visibility of all gate edges is provided from the exterior of the housing so as to give a positive indication that the gate or blind has passed completely through the seals. In addition, the present line blind valve provides for lockout when the gate or blind is closed.
The present invention also provides an improved construction as compared to previous valves by a special arrangement of the sleeve structure and a stiffener ring at opposite sides of the gate or blind and with the sleeve having a novel coaction with the gate or blind and mounted in a novel manner in the valve housing.
The present invention employs a valve construction which is based on the resilient seating of elastomer seals or sleeves against a sliding gate or blind. As the gate or blind slides between the sealing sleeves during the valve opening or closing operation, the opposing sleeves are caused to move axially, coming together and separating respectively. Since the sleeves are made of non-compressible resilient elastomers, the sleeve material displaced by the gate or blind must move or flow into open areas or spaces designed to receive such movement.
In prior art valves, the open areas have been provided in the valve housing by allowing the sleeves to flow radially outward, thus enlarging the sleeve outside diameter. In addition, some valves have provided for radially inward movement into the inside opening of the sleeve where the process slurry flows.
By the present invention, open areas for receiving elastomer movement are located internally within the sleeve. This configuration has several advantages:
1. It allows a snug fit of the sleeves in the housing providing maximum support of the sleeves. PA1 2. It allows for a wider range of valve sizes including larger diameter valves. PA1 3. Internal movement of the sleeve has less resistance to the flow of the elastomer thus reducing the force required to actuate the valve. This is an economic consideration which reduces the size and cost of the valve actuator. PA1 4. The concept also provides economies in the manufacture or molding of the elastomer sleeves. Pins that support the sleeve's metal stiffener ring in the mold leave the internal openings in the sleeve when it is removed from the mold. These remaining openings receive the elastomer movement when the valve is actuated. Since the metal stiffener ring is encapsulated in the sleeve with no part of it exposed, corrosion resistant metal such as stainless steel is not required thus reducing the overall sleeve cost. PA1 5. A ported gate or blind can replace the standard knife gate or blind simply by removing the knife gate or blind and sliding the ported gate or blind into position and pinning it to the actuator clevis. The knife gate or blind sleeves are then replaced with shortened sleeves for the ported gate or blind. No modifications are required on the valve housing or actuator.
Accordingly, it is an object of the present invention to provide a line blind valve having all edges of the gate or blind visible from the exterior and with provision for lockout when the gate is closed.
It is a further object of the present invention to provide a gate valve or line blind valve assembly having improved features as to operation of the sleeve members with the gate or blind.
It is another object of the present invention to provide a novel gate valve or line blind valve assembly wherein resilient sleeve units at opposite sides of the gate or blind are mounted in a special manner in the valve housing and have special coaction with the relatively slidable gate or blind.
A further object of the invention is to provide a novel gate valve or line blind valve assembly wherein the inner ends of axially compressed sleeve units engage opposite sides of the gate or blind in the valve closed condition and sealingly engage in the valve open condition, and are of special structure providing improved coaction between the sleeve units and the gate or blind.
A further object of the invention is to provide a novel gate valve or line blind valve assembly wherein each sleeve end at the gate or blind is of a specific configuration and with a stiffener of novel construction and location being provided to maintain the sleeve in position when the gate or blind is opening or closing.
Another object of the invention is to provide a novel gate valve or line blind valve assembly wherein opposed sleeve units under axial compression are coaxially mounted in a novel manner in a valve housing.
Further objects of the invention will be apparent from the following description as taken with the appended claims and the accompanying drawings.